Grantee Research Project Results
2003 Progress Report: Microbial Community Diversity, Structural and Functional Responses to Multi-Component Metal Contamination of River Benthic Systems
EPA Grant Number: R829400E02Title: Microbial Community Diversity, Structural and Functional Responses to Multi-Component Metal Contamination of River Benthic Systems
Investigators: Holben, William E. , Gannon, James , Moore, Johnnie , Rillig, Matthias
Current Investigators: Gammons, Christopher H. , Hobbs, David , Nimick, David , Moore, Johnnie
Institution: University of Montana
Current Institution: University of Montana , United States Geological Survey
EPA Project Officer: Chung, Serena
Project Period: September 24, 2001 through September 23, 2003 (Extended to September 22, 2004)
Project Period Covered by this Report: September 24, 2002 through September 23, 2003
Project Amount: $280,000
RFA: EPSCoR (Experimental Program to Stimulate Competitive Research) (2000) RFA Text | Recipients Lists
Research Category: EPSCoR (The Experimental Program to Stimulate Competitive Research)
Objective:
The objective of this research project is to develop detailed information about the composition, physiological activities, and chemical environment of microbial communities in river sediments contaminated with mine wastes. These experiments test five hypotheses: (1) initial exposure to metals inhibits or kills sensitive organisms, leaves tolerant populations as dominant, and produces an initial net decrease in diversity; (2) gradual changes in microbial community structure and function occur as the resident community becomes more tolerant of metal contamination; (3) decreased apparent toxicity from metal contamination occurs with prolonged exposure as a result of increased tolerance; (4) bacterial community changes can be indicative of the ecological health of watersheds because of the primary role bacteria play in biogeochemical processes and their basal position in ecosystem trophic structure; and (5) microbial communities respond to perturbation through changes in abundance of specific populations, or through altered patterns of physiological/metabolic activity.
Progress Summary:
Using a suite of methods (denaturing gradient gel electrophoresis (DGGE), 16S rRNA phylogeny, phospholipid fatty acid analysis (PLFA), direct microscopic enumeration, and quantitative polymerase chain reaction), we compared the microbial communities inhabiting the hyporheic zone of six different river sites that encompass a wide range of sediment metal loads resulting from large base-metal mining activity in the region. There was no correlation between sediment metal content and the total hyporheic microbial biomass present within each site. Microbial community structure, however, showed a significant linear relationship with the sediment metal loads. The abundance of four phylogenetic groups (Groups I, II, III, and IV) most closely related to , , and -proteobacteria, and cyanobacteria respectively, were determined. Sediment metal content was positively correlated with Group III abundance and negatively correlated with Group II abundance. No correlation was apparent with regard to Group I or IV abundance. This is the first documentation of a relationship between fluvially deposited heavy metal contamination and hyporheic microbial community structure.
We next assessed whether relationships between hyporheic microbial community structure and heavy metal contamination vary seasonally. No relationship between total bacterial abundance and heavy metals was observed (R2 = 0.02, p = 0.83). We demonstrated a strong and consistent linear relationship, however, between the percent difference in microbial community composition (populations present) and the difference in heavy metal content of hyporheic sediments throughout the year (R2 = 0.58, p < 0.001). Correlations between heavy metal contamination and the abundance of four specific phylogenetic groups noted were apparent only during the fall and early winter, when the majority of organic matter is deposited into regional streams. These data suggest that the abundance of susceptible populations responds to heavy metals primarily during seasons where the potential for growth is highest.
Next, we performed controlled laboratory experiments to measure rates of change in hyporheic microbial communities in response to heavy metal contamination. Community-level responses were monitored at 1, 2, 4, 8, and 12 weeks using group-specific primer sets for indigenous populations (described above). There was a consistent, strong curvilinear relationship between community composition and heavy metal contamination (R2 = 0.83, p < 0.001), which was evident after only 7 days of metal exposure (i.e., short-term response). The abundance of each phylogenetic group was negatively affected by the heavy metal treatments; however, each group recovered from the metal treatments to a different extent and at unique rates. The structure of hyporheic microbial communities responded rapidly and at contamination levels an order of magnitude lower than those shown to elicit a response in aquatic macroinvertebrate assemblages.
Collectively, these data indicate that hyporheic microbial communities are a sensitive and useful indicator of both long-term and short-term effects of heavy metal contamination in streams.
Future Activities:
We will focus on determining which metals in the contaminant mixture in the environment exert the greatest effect on community structure and function. We also will focus on quantitatively assessing the degree of metal-tolerance in individual microbial populations and the total community as one moves along the contamination gradient.
Journal Articles on this Report : 4 Displayed | Download in RIS Format
Other project views: | All 36 publications | 12 publications in selected types | All 11 journal articles |
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Feris KP, Ramsey PW, Frazar C, Rillig MC, Gannon JE, Holben WE. Structure and seasonal dynamics of hyporheic zone microbial communities in free-stone rivers of the western United States. Microbial Ecology 2003;46(2):200-215. |
R829400E02 (2003) R829400E03 (Final) |
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Feris KP, Ramsey PW, Frazar C, Rillig M, Moore JN, Gannon JE, Holben WE. Seasonal dynamics of shallow-hyporheic-zone microbial community structure along a heavy-metal contamination gradient. Applied and Environmental Microbiology 2004;70(4):2323-2331. |
R829400E02 (2003) R829400E03 (Final) |
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Feris KP, Ramsey PW, Rillig M, Moore JN, Gannon JE, Holben WE. Determining rates of change and evaluating group-level resiliency differences in hyporheic microbial communities in response to fluvial heavy-metal deposition. Applied and Environmental Microbiology 2004;70(8):4756-4765. |
R829400E02 (2003) R829400E03 (Final) |
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Feris K, Ramsey P, Frazar C, Moore JN, Gannon JE, Holben WE. Differences in hyporheic-zone microbial community structure along a heavy-metal contamination gradient. Applied and Environmental Microbiology 2003;69(9):5563-5573. |
R829400E02 (2003) R829400E03 (Final) |
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Supplemental Keywords:
microbial community, heavy metal, DNA, mining, restoration, indicators, Montana, MT, PCR, microbial community structure, perturbation, hyporheic sediments, heavy metal contamination, sediment metal loads., RFA, Scientific Discipline, INTERNATIONAL COOPERATION, Waste, INDUSTRY, Water, Geographic Area, Ecosystem Protection/Environmental Exposure & Risk, POLLUTANTS/TOXICS, Environmental Chemistry, Arsenic, State, Chemicals, Fate & Transport, Monitoring/Modeling, Microbiology, Hazardous Waste, Environmental Monitoring, Industrial Processes, Water Pollutants, Ecology and Ecosystems, Hazardous, EPA Region, fate and transport, monitoring, aquatic ecosystem, contaminant dynamics, fate and transport , contaminant transport, mine tailings, mining, Region 8, analytical chemistry, chemical kinetics, chemical releases, groundwater contamination, Montana , chemical transport models, heavy metals, groundwater, mining wastes, mining impacted watershed, stream ecosystemProgress and Final Reports:
Original AbstractThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.